Stripping of explosive cartridges



E (fiumi D. 'MITCHELL 2,663,441

STRIPPING OF EXPLOSIVE CARTRIDGES Filed Jan. 7. 1952 Dec. 22, 1953DUGALD MITCH ELL.

MW, 043,7 0 @tij/MWL ATTORNEYS Patented Bec. 22, 1953 STRIPPING FEXPLOSIVE CARTRIDGES Dugald Mitchell, Saltcoats, Scotland, assigner toimperial Chemical Industries Limited, a co1'- poration of Great BritainApplication January 7, 1952, Serial No. 265,319

Claims priority, application Great Britain March 8, 1951 12 Claims.

This invention is concerned with improvements in the stripping orunwrapping of blasting explosive cartridges.

In the production of cartridges of gelatine, semi-gelatine and powderedexplosives itis sometimes necessary to unwrap or strip cartridges fromtheir wrappers and repack them, for eXn ample, in different sizes.Formerly, stripping has been achieved by an operator holding thecartridge, opening the ends by means of a pointed stick and thereafterunwinding the wrapper by pulling it clear which necessitates the use oiboth hands. .The explosive portion is then put in a bin to be re-wrappedor re-Worked and the wrapper put into another bin for subsequentdestruction, for example, by controlled burning. This method ofoperation has many and varied disadvantages; thus the operator requiresto handle the unwrapped explosive; the method is slow and cumbrous anddoes not allow the operator to develop a smooth rhythm. such as wouldlead to high rates of throughput.

The object of the present invention is to provide a process which willfacilitate the unwrapping or stripping of explosive cartridges, whichcan be carried out without necessitating the handling of unwrappedexplosives by operators and which allows of a high rate of throughput.

I have now found that this object can be achieved by a processcomprising passing a wrapped cartridge or a gelatine, semi-gelatine orpowdered blasting explosive through an apparatus comprising a means forrotating sai wrapped cartridge, means ior simultaneously applying agradually increasing pressure to its cylindrical surface until the endsof the wrapper unfold and the outer edge thereof has become free, anddischarging means for delivering the partly unwrapped cartridge forinstance to an operative for completion of the separation oi theexplosive from the wrapper.

According to the present invention the process for stripping blastingexplosive cartridges oi substantially cylindrical form comprisessubjecting a cartridge while undergoing rotation to gradually increasingpressure applied to its cylindrical surface until the ends of thewrap-per unfold and the outer longitudinal edge of the wrapper becomesfree and forms a partially unrolled portion and then separating theexplosive from its wrapper.

To separate the explosive from its wrapper an operative for instance canhold said unrolled portion in the hand and shake out the explosive.

Apparatus according to the invention comprises in combination arotatable roller and a stationary plate, wherein the stationary plateforms with the roller an entry end and an exit end and a spacialdistance decreasing gradually from the entry end to the exit end,wherein the roller has projections positioned thereon substantiallyparallel to the longitudinal axis, and wherein the stationary plate hasprojections parallel to those on the roller and on the side of the platefacing the roller.

The said apparatus preferably includes discharging means and means foradjusting the distance of the plate from the rotatable roller.

The stationary plate may have a plane surface facing the roller or maybe concave with respect to the roller. The stationary plate may be arigid sieve or a grid which is particularly desirable if the cartridgesto be treated contain powdered er plosives. Furthermore the stationaryplate is preferably spring loaded.

The rotatable roller may be an endless belt of semirigid material.

For cartridges of normal size the diameter of the roller can be 8 inchesand the projections of the roller may conveniently be 1l.;- inch. Theroll er should be capable of revolving at a rate of 20-40 and preferablyabout 30 revolutions per minute, and the narrowest distance apartbctween the rotatable roller and the stationary plate lies preferablybetween 1 inch and 1/1 inch. A cartridge of l'e inches is found torequire the maximum narrowest distance apart between the roller and thexed plate of l inch and a cartridge of q1@ inch a narrowest distanceapart of el: inch in order to effect the unfolding of the ends and thefreeing of the outer longitudinal edge of its wrapper.

When using the apparatus the cartridge is fed in at the end of greatestclearance with its length approximately at right angles to the directionof travel and is positioned and gripped by the transverse bars orprojections and then carried to the end of decreased clearance whilebeing rotated and having a gradually increasing pressure applied to itscylindrical surface. At the end of the plate or grid the cartridge dropson a sheet which carries it to a tray from which the operative lifts itby the unrolled portion of the wrapping, shakes the explosive portioninto a bin and deposits the waste wrapper in a further bin. By suitablepositioning the operative can feed two cartridges simultaneously, onewith each hand, and the apparatus can be controlled in such a way thatwhile two cartridges are going through between the roll and the plate orgrid the operator is shaking out the two precedn ing cartridges.

The invention is illustrated with reference to the diagrammatic drawingaccompanying the specification which shows a sectional elevation of apreferred apparatus for carrying out the process of the invention forgelatine or semigelatine.explosives. In the drawing, l is a rotatableroll of 8 inches diameter capable of rotating at 30 revolutions perminute and having longitudinal bars or projections 2 of le inch height*mounted thereon, 3 is a curved plate rlttedfwith` similar longitudinalbars or projections 4,' 5 is an arm supporting the plate-3, 5i is asprung shaft supporting the ends of the arms 5, l is a guard supportedby the bearing assembly 3, 9 is a hand wheel which operates an adjustingpin Il)v through the nut Il which is iixed to the frame I2. I3 is aspring to hold the platee imposition,

I4 is a chute leading to the tray l5, and I6 is tl'iefeed opening of theapparatus. 3', 9s' and l0 show alternative positionings of the curvedplate 3, the hand wheel 9 andtheadjusting p in Hl.

In Vusing thisv apparatus the clearance between the plate 3 and the rolll is first adjusted according *to the diameter of cartridge in use bymeans of the adjusting pin i6. The adjustment is preferably such thatthe narrowest clearance is l inch for a cartridge of lfe inches and inchfor a cartridge of 1l@ inch.l The cartridge is then fed in through theopening h3 with its length approximately parallel to that ci the roll lwhich is rotated in an anti-clockwise direction. The cartridge is guidedbetween the roll and the plate and is then carried along and rotatedwhile an increasing pressure is applied to it so that by the time itfalls over the end of the plate 3 on to the chute i4 which carries it tothe tray l5 the ends of the Wrapper of the cartridge uniold and theouterlongitudinaledge orV thewrapper becomes free and forms a partiallyunrolled portion.Y The operative then picks up thethus treated cartridgeby the unrolled portion of thewrapper, shakes theexplosive portion outinto a bin and deposits the wrapper in a furtherbin.

What-I claim is:

l. A process for stripping blasting explosive cartridges ofsubstantially cylindrical form which comprises subjecting a cartridgewhile undergoing rotation to gradually increasing pressure applied toits cylindrical surface until the ends of the wrapper unfold and theouter longitudinal edge of the Ywrapper becomes free and forms apartially unrolled portion and then separating the explosive from itswrapper. Y

2. A process as claimed in claim 1 wherein the explosive is separatedfrom its wrapper by holding said unrolled portion and shaking out theexplosive.

3. Apparatus comprising in combination a ro- Y tatable roller and astationary plate in which apparatus the stationary plate forms with theroller an entry endand an exit end and a spacial distance decreasinggradually from the entry end to the exit end, the roller has projectionspositioned thereon-substantially parallel to its longitudinal axis, andthe stationary plate has projections parallelto. those onithe roller andon the side of the plate facingthe roller. A

4; Apparatusas claimed in claim 3 which includes means for adjusting thedistance of the plate; from the rotatable roller.

5. Apparatus as claimed in claim 3 wherein the stationary platehasaplane surface facing the roller.v

6. Apparatus as claimed in claim 3 wherein the stationary plate isconcave with respect to the roller.

'7. Apparatus as claimed in claim 3 wherein kthe stationary plate is arigid sieve.

8. Apparatus as claimed in claim 3 wherein the stationary plate is agrid.

9. Apparatus as claimed in claim 8 wherein the rotatable roller is anendless belt of semi-rigid material.

l0. Apparatus as claimed in claim 3 wherein the stationary plateisspring loaded.

1l. Apparatus as claimed in claim 3 wherein the diameter of the rollerlis 8 inches, the projections of the roller areqlg inch, the. roller isadapted to` revolve at a rate of V2040 revolutions per minute, and thenarro'west distance apart between the rotatable roller and thestationaryplate lies between'. l inch and V4, inch;

12. Apparatus as claimed in claim 3 which in'- cludes; dischargingmeans.

DUGALD MTCHELL.

References Citedin the iler of this patent UNITED STATES PATENTS Number

